Chapter Three: Backward Induction

No. 12 Grimmauld Place
13th December 2009, 9.36am

Unaware that he was shortly expecting visitors, Harry Potter, former Auror and now (officially speaking) gentleman of leisure, was at that moment brushing his teeth and studying his reflection in the mirror above the sink. The bruise around his right eye had almost entirely faded, and you could only see the shallow scratches on his cheek if you were really looking for them.

"Admiring yourself, are you?" the mirror asked dryly, and Harry scowled in response, before bending forward to spit toothpaste into the sink.

"Oh, very uncouth," the mirror sniffed as he rinsed his mouth with icy water from the tap. "Anyone would think you were a common Muggle."

"Did I ask for your opinion?" Harry huffed, setting his toothbrush back in the cup and dragging a hand through his overlong hair.

"You never do," the mirror said, with a mournful sigh, and Harry rolled his eyes as he turned and left the bathroom to head downstairs.

Number 12, Grimmauld Place bore little resemblance to the dingy townhouse Harry had known while Sirius was still alive. Over the years, the cautious truce with Kreacher had grown into something resembling a grudging mutual affection, and when Harry had sat down to tentatively propose some remodelling the elf had surprised him by producing the original plans for the house and making a number of his own suggestions.

It had been Kreacher's idea, for example, to install the tall french doors that opened onto the (alarmingly wild) back garden, flooding the kitchen with pale winter sunlight that fell brightly onto Hermione Granger's shoulders where she sat at the table reading a newspaper.

"Oh," Harry said, coming to an abrupt stop in the doorway. "I didn't hear you come in."

"Home invasion," Hermione commented without looking up. "You shouldn't leave your Floo open."

"Master has a visitor!" Kreacher popped out of thin air, his arms filled with what appeared to be pine cones, and bowed deeply to Harry before turning his head slightly towards Hermione. "Is Master wishing Kreacher to expel the Mudblood One from his presence, or to make tea?"

"I think tea will do for now, thanks," Harry said. "And maybe later we can have a refresher course on how you address my friends."

"He doesn't mean any harm," Hermione murmured. She still hadn't looked up from the newspaper, and Harry watched as a familiar line appeared between her eyebrows. "Something's happened in Diagon Alley."

"Oh yeah?" Harry replied, sliding into the chair opposite her. "What sort of something?"

"It doesn't say," she answered, spinning the paper and pushing it across the table towards him.

The Prophet had devoted their entire front page to a gigantic headline - MYSTERY INCIDENT AT GRINGOTTS BANK - beneath which was a photo of Ron shouldering his way through a crowd. Seeing Harry, the photo-Ron smiled and waved, apparently forgetting his duties for a moment, before disappearing behind an emergency perimeter ward. Harry pulled the paper closer and scanned the article quickly - no details released at this time - Aurors still onsite - rumours of multiple casualties - no comment from St Mungo's -

"'Get the full story, only in today's Evening Prophet,'" Harry read aloud. "Do you reckon Callie knows Rowan's promising an exclusive?" he smirked, accepting a mug of tea when Kreacher appeared at his side and sipping it without thinking. "Ouch, fuck, Kreacher that's too -"

"Master will watch his tongue, lest it is worse than burnt," Kreacher sniffed, handing another mug to Hermione, who used it to hide her smile. "Will Master and the Mudblood One be requiring anything else, or may Kreacher be permitted to finish decorating the parlour?"

"Decorating the - wait, what are you doing?" Harry yelled up the stairs as Kreacher disappeared. "Did he tell you what he was doing?" he asked, looking back at Hermione.

"I think 'decorating the parlour' is fairly self-explanatory," Hermione said mildly, blowing on her tea before bringing the mug to her mouth. Her eyes sparkled over the top of it, and Harry sighed, tossing the paper back on the table and then wincing when the motion pulled at the ribs that had been broken twelve hours before, and were still slightly tender.

Hermione caught the expression and frowned. "How are you feeling?"

"Like I got in a fight with a teenage centaur," Harry sighed, rolling his shoulder carefully. "Which I guess is about right."

"I told you to take that pain potion," Hermione's voice was resigned.

"And I told you I can't think properly when I've had it," Harry replied. "Besides, you did a decent enough job fixing me up."

"You were lucky I was around," Hermione set her tea down and reached across to press her fingers gently against the remnants of swelling below his eye. "For all you knew I could have been on a hot date."

"Could you?" Harry made no attempt to hide the surprise in his voice, trying and failing to get a look at Hermione as she took hold of his chin and turned his head to examine the scratches from the centaur's fingernails.

"I was supposed to have dinner with Neville," she murmured. "But he had to work late."

"He always did have a crush on you," Harry said, his tone teasing.

An unfamiliar expression flitted across Hermione's face and she abruptly released Harry's chin, her hand hovering uncertainly in the air before she picked up her tea again. "Yes, well. In any case I should know better by now than to try and schedule social events when you're likely to end up in peril."

"I hardly think a fistfight with a centaur qualifies as peril," Harry muttered, still trying to place the look that had briefly passed over Hermione's features.

"Oh really?" she retorted, with what Harry thought was possibly unnecessary sharpness. "Tell that to your eye."

"I -" Harry started, then his ribs gave another twinge and he decided that it wasn't worth arguing. "Fine. Did Kingsley say whether the Aurors had found Gorman?"

"Owled this morning," Hermione nodded. "Apparently Improper Use of Magic raided Gorman's camp last night after an unusual surge was reported. Found him out of his mind on pixie dust with about 15 computers. I imagine it'll take them most of the week to work out how he was connected to the internet."

Gorman, the centaur who had left his mark on Harry's face and ribs, had been using his divinatory powers to achieve an uncanny run of luck in the Fantasy Premier League. So uncanny, in fact, that the Essex Police's Fraud Squad had decided to have a look into who, exactly, was behind IlPegasi89's winning streak.

Like all British police forces, they input the case details into their central computing system, which ran a keyword search against other criminal investigations. It turned out that there were just enough flags in the initial report on Gorman's activities for the case to be referred to a unit called Specialist Crime Directorate 9.

Which was where Harry had come in.

oOo

Four years earlier

Though he was loath to admit it, it had been the appearance at No. 4, Privet Drive of several rather impressive wizarding strangers the summer that he and Harry had both turned seventeen that had inspired Dudley Dursley to look seriously into the possibility of joining the Army. Once his father's death and his mother's ailing health made the prospect of overseas deployment less attractive, he had changed his mind, and had instead applied to the Metropolitan Police.

Dudley had joined the force straight out of school, and had been surprised to find how much he enjoyed the work. What had been possibly even more surprising was that he was actually good at it, and he had just earned his sergeant's stripes when he received a phone call from Royal Surrey County Hospital to inform him that his mother had been admitted and would he please be able to come in as a matter of urgency.

They buried Petunia on a bleak, drizzly day in late October. Dudley wore his full dress uniform, and sat through the service at the crematorium feeling numb with more than cold. Afterwards, there was a small wake in the receiving room, attended by a few neighbours and a couple of distant relatives on his dad's side. Dudley clutched a glass of water throughout, and tried to pretend that he wasn't constantly looking over the shoulders of people who came to offer their condolences. Despite his best efforts, his eyes kept seeking the door, which remained resolutely closed, admitting no one else.

When everyone had gone, he made his way back to stand at Petunia's graveside and stare at the mound of earth that hid her tasteful cherrywood coffin, wondering how he was supposed to be feeling. He wasn't entirely certain, but he didn't think relieved should have been quite so high up on the list of emotions.

Behind him, someone cleared their throat, and Dudley turned to see Harry standing there, wearing an improbably smart suit and an expression of strained determination.

For what felt like an incredibly long time, but was likely no more than ten seconds, neither of them said anything. Harry seemed to be sizing him up, and Dudley realised that he was doing the same thing.

His cousin looked good: there was no other word for it. He was as tall as Dudley, and though much narrower in build he had the wiry, fit look of someone who knew how to handle himself. His hair was as messy as ever, but Harry appeared to have grown into it, looking less like an urchin and more like someone who should be striding around moors in one of the period romances that Petunia had so adored.

"Where the hell have you been?" Dudley asked gruffly, and behind his glasses (lightweight tortoiseshell, miles away from the much-repaired NHS set he used to sport) Harry winced.

"Couldn't get away from work" he said quietly, which didn't exactly cover the last seven years. His hands were stuffed deep into the pockets of his navy greatcoat, but Dudley had the impression that they were probably clenched into fists. "How was it?"

"How do you think it was?" Dudley sighed. "Fucking awful."

"I hate funerals." Harry scuffed at the muddy ground with the toe of one shoe, before looking back up at Dudley. "Fancy a drink?"

"Like you wouldn't believe," he replied gratefully.

Harry took him to a pub just off Streatham Common, and as they walked through the door Dudley felt the odd, fizzing sensation on his skin that he had come to associate with his cousin's "funny business." The place was almost empty, and when the barman caught sight of them his eyebrows rose to meet his shaggy hairline.

"Two pints of Ballycastle Bitter please, Marcus," Harry said, and after a brief pause the man nodded and started pulling the drinks.

"He's pretty discreet," Harry said quietly, once he'd ushered Dudley over to a table in the corner. "His father went to prison after the war but Marcus turned - well -" he frowned slightly, eyes roving once again over Dudley's uniform "- I guess you'd call it state's evidence."

"The war," Dudley repeated, cautiously tasting his beer and finding it smooth, hoppy, and surprisingly pleasant.

"Yeah," Harry nodded. "That was a whole... thing."

It took another four pints for him to tell the story, and Dudley listened with quiet disbelief as Harry revealed everything that had happened since he'd been whisked away from Privet Drive the night before his seventeenth birthday. Somehow the least unexpected aspect of the whole tale was that Harry was now a relatively senior wizarding policeman - or Auror, as he called it. He exuded the same air of quiet authority that Dudley was used to from the most competent officers he'd worked with.

"I wasn't surprised when I heard you'd joined the Police," Harry said, echoing Dudley's thoughts, but making him pause with his glass halfway to his mouth.

"Where did you hear that?"

Harry's mouth lifted into something that wasn't exactly a smile. "I've been keeping tabs," he replied. "I didn't want to intrude, because I wasn't sure - but I thought - shit." He placed his glass on a paper coaster advertising something called cauldron cakes, and ran his fingers through his tousled hair. "I appreciate that this is fairly crappy timing, but I've been meaning to talk to you for a while."

Dudley set down his own glass, more intrigued than offended by Harry's awkward demeanour. "What about?"

"So, me and my skipper have noted an 'alarming rise' in Muggle-adjacent crime in the last few months," Harry said, making quotation marks with his fingers and affecting a scots accent that was, in itself, quite alarming. (When Dudley eventually met Emilius Ogden, he would be struck by the accuracy of the impersonation). "Emilius took it to the Minister for Magic, who approached the Home Secretary, and - well, anyway. They've agreed to implement a task force of Aurors and police to work together on this, and I was wondering if you'd be interested in -"

"I'd be up for joining it, yeah," Dudley nodded, promptly deciding to blame his own eagerness at the prospect on the amount he'd had to drink.

"Well." Harry's not-quite smile had broadened. "We had a look at your record, and Emilius was actually thinking you might want to head it up."

oOo

No. 12 Grimmauld Place
13th December 2009, 9.43am

"Good," Harry sighed, satisfied that Gorman's case was now safely in the hands of the DMLE. "And they don't suspect -"

"As per usual, you've covered your tracks remarkably well," Hermione said. "Though pixie dust, really, Harry?"

"Hey!" Harry held his hands up to protest his innocence. "It was his own supply, and I only gave him enough to mask the Obliviation."

Hermione pursed her lips in mock disapproval, her odd behaviour of a few moments before seemingly having disappeared. "If you were my client I'd be telling you -"

"Ah," Harry grinned. "But I'm not your client, I'm your business partner, so -"

"Silent business partner," Hermione corrected him. "Which, frankly, is how I prefer you."

"And isn't the devil in the detail," Harry sighed. "Anyone would think you were a lawyer."

"Ha bloody ha," Hermione rolled her eyes, before draining the rest of her tea. "Anyway, I was thinking I might try and get hold of Callie and see if she knows any more about this Gringotts thing than -"

She was interrupted by a crash from the floor above, and the pair of them stared at one another for a moment before both pushing their chairs back and bolting for the stairs. When they reached the parlour, Harry was startled to find every surface covered by a proliferation of what appeared to be late-Victorian Christmas ornaments. Kreacher was standing in the middle of the room, levitating a heavy-looking garland into place above the mantelpiece.

"Kreacher?" Harry asked hesitantly. "Where on earth did all this come from?"

"Kreacher is finding Mistress Violetta's Yule things in the seventh attic," the elf replied, sounding worryingly breathless.

Seventh? Hermione mouthed at Harry, who shrugged. The house was forever revealing new pockets of itself, as the concealment charms either wore out or decided that Harry had finally proved himself trustworthy enough to use the upstairs drawing room.

"Well," Harry said after a moment's consideration of the parlour's new incarnation as a nineteenth-century Santa's grotto. "It looks - great?"

"Good enough for Master to invite guests?" Kreacher let the garland come to rest on the wall and turned to blink hopefully at Harry.

"Er -" he said. "Yeah, sure. Why not? Although -" he noted Kreacher's bent posture, and increasingly wizened appearance "- are you sure you're up for that, I mean it'll probably be Ron and his lot, and they're always -"

Kreacher straightened his back with an audible creak, his face turning mutinous as his ears flared to the sides. "Kreacher is not ready to be mounted on the wall of his forefathers quite yet, Master."

Harry heard Hermione give a stifled cough of laughter, and turned to ask her whose side she was on, before noticing that one half of her face seemed to be lit in flashing blue. "What -"

His pocket started buzzing, and a familiar marimba tune began to play. Kreacher shot the phone a look of utter loathing as Harry pulled it out and frowned at the screen, before pressing the green icon to answer the call.

"Black & Lupin Consulting," he said, watching as Hermione, in search of the source of the light, crossed the room to look out of the window. "How can I -"

"I've got a surprise for you," said Sahra Guleed, just as Hermione turned and motioned urgently for Harry to join her.

When he looked down to the street, he could see Guleed waving from the pavement outside. She wasn't quite looking at the house, but she wasn't quite not looking at it either. Behind her, a grey BMW was parked at the curb, the blue light that Harry had seen reflected on Hermione's cheek flashing from behind its engine grille.

"What sort of surprise?" he sighed.

"A murder victim that we think is one of yours," Guleed said, sounding unnecessarily gleeful. "And a suspect in custody who's definitely one of yours."

"In custody?" Harry asked. Hermione met his eye, her eyebrows rising into a silent question. "At West End Central?"

"Got it in one." He could see Guleed grinning from here. "Fancy a trip to Savile Row, Mr Potter?"

"I'll get my coat," Harry said, hanging up before Guleed could offer to put him in handcuffs. He wasn't sure, but he suspected it constituted a twisted form of flirting on her part. "Dudley thinks he's got a murderer," he told Hermione, who frowned.

"In Muggle London?"

"Sounds like it," Harry said over his shoulder as he strode out of the room. "He knows what he's looking for, and he's got the Priori potion, so I doubt he'd -"

"But who would be stupid enough to let themselves get caught by the Muggle police?" Hermione had followed him into the hall, and was standing by the front door with her arms folded, her forehead puckered in puzzlement.

"Sahra didn't say," Harry shrugged as he pulled on his coat, and watched Hermione's face darken slightly at the mention of Guleed. For some reason the two of them had never really seemed to get on.

"Do you want me to come with you?" she asked, and Harry shook his head.

"Send an owl to Kingsley first, let him know we might have some trouble on our hands," he said. "Then meet me at the station after." He glanced at the grandfather clock that stood austerely against the opposite wall. "They change the duty solicitor at half ten, so -"

"Yep," Hermione nodded, then waved her wand at her robes, silently transfiguring them into a neat Muggle skirt suit.

Harry paused with his hand on the door handle, momentarily distracted by the way Hermione's silk blouse set off her olive skin.

"What?" she asked, giving him another funny look.

"Nothing," Harry jolted himself back to the matter in hand, and pulled open the door. "See you in a bit."

"There you are," Guleed said, as he stepped off the doorstep to join her on the pavement. "I thought I was finally going to be able to arrest you."

Standing nearly a foot taller than the diminutive police officer, Harry gave her an incredulous look. "You and whose army?"

"I'm sure Jack would have helped," Guleed grinned, jerking her head towards the car, where a man was sat forward in the driving seat, staring over the steering wheel with a look of utter perplexity as he patently tried to figure out where Harry had appeared from.

"Alright?" Harry nodded to him as he opened the rear passenger door and slid into the car behind Guleed.

"You don't look like a CI," the thin-faced policeman remarked as he started the engine.

Harry saw Guleed smirk in the rearview mirror, and scowled. "For fuck's sake," he muttered. "I'm not an informant, I'm a consulting detective."

A/N: major props to cocoartist for some truly stellar proof-reading.